Hypodermic needles



July 26 1960 5. J. EVERETT HYPODERMIC NEEDLES Filed March 21', 1958Ill/III fir/ll Inventor I a Samuel J 8 Ev 4 at w Attorneys United StatesPatent HYPODERMIC NEEDLES Samuel James Everett, Surrey, England,assignor to S. & R. J. Everett & Company Limited, Surrey, England, aBritish company Filed Mar. 21, 1958, Ser. No. 723,003

Claims priority, application Great Britain Mar. 27, 1957 3 Claims. or.18-36) In order to secure hypodermic needles in their mounts it isfrequently the practice to die cast the mount directly onto the needle.The mould used for this purpose has a hole at one side for the insertionof the rear end of the needle and at the other side an opening is leftfor the insertion of a tapered core pin which, during casting, forms therecess in the body of the mount which ultimately fits over the nozzle ofthe syringe. mount has been cast there must, of course, be directcommunication between the recess and the bore in the needle and toprevent the flow of metal into this bore during casting, the core pin isformed with a sharply tapered point which enters the bore of the needle.During the casting process the needle is held firmly against this pointand this proves quite efiective in preventing the metal from enteringthe bore of the needle. It is somewhat difiicult, however, to press theneedle effectively against the point on the core pin and in quantityproduction a relatively large proportion of faulty mounts are produced.This renders the process costly both in labour and material and,moreover, the mould upkeep is expensive since the core pins inparticular require frequent replacement.

According to the present invention the tip of the core pin is fittedwith a resilient sealing member for closing the rear end of the bore ofa needle instead of with a sharp point for insertion into the bore. Thissealing member is pressed against the rear of the needle and provides acushioning effect enabling an extremely effective seal to be producedwithout any appreciable difiiculty in holding the needle in position.The seal produced is, in fact, so eflicient that it is possible to use asynthetic plastic material such as polythene or nylon for the body ofthe mount in place of the metal previously used. This has not previouslybeen practicable owing to the fact that it is considerably moredifiicult to obtain a seal when using a plastic material of this naturethan when using metal.

Preferably the sealing member is retained within a recess in the tip ofthe core pin. The member may be held in position by means of an axiallyextending rod engaging the rear of the member and controlled by means ofa screw at the rear of the core pin. This rod may be designed so as toapply a variable degree of compression to the member, so as to allow forthe effects of wear. The sealing member may conveniently be made ofrubber or of similar rubbery material such, for example, as siliconerubber.

Examples of constructions in accordance with the invention will now bedescribed in more detail by way of example with reference to theaccompanying drawings in which; 7

Figure 1 shows a general arrangement of a mould in accordance with theinvention during the process of moulding a mount onto a hypodermicneedle;

Figure 2 is a cross sectional view to an enlarged scale of part of acore pin shown in Figure l; and

When the a 2,946,093 Patented July 26, 1960 ice Figures 3 and 4 areviews corresponding to Figure 2 of modified forms of core pin. Referringfirst to Figure 1 a mould shown as 1 is used for the production of amount 2 for a hypodermic needle 3. The mount 2 is formed at its rear endwith a recess which is ultimately intended to fitover the nozzle of ahypodermic syringe but which during moulding is occupied by the end of acore pin 4 which closes the rear end of the mould 1. The mould 1 isformed with an inlet 5 for the moulding material which, as previouslymentioned, may be either a metal or a synthetic plastic material such aspolythene or nylon.- The mould 1 is split so that after the mouldingprocess is complete it may be removed from the completed mount 2.

During the moulding operation it is essential that the moulding materialshould be prevented from entering the bore of the needle 3 and for thispurpose the rear end of the bore requires to be pressed tightly againstthe tip of the core pin 4. The mould 1, together with the core pin 4, isfirmly held in position on a support (not shown) while the needle 3 isengaged by a point locator 8 acted on by a spring 9, the other end ofwhich abuts against a surface 10. The thrust of the spring 9 forces theend of the bore of the needle 3 against the tip of the core pin 4 wherea seal is etfectedby means of a resilient sealing member 12 seen in moredetail in Figure 2.

This member is made of a rubbery material such as silicone rubber and isfitted within a recess in the core pin 4. It is held in position bymeans of an axially extending rod "13 controlled by means of a screw 14which is screwed into a tapped bore 15 in the rear end of the core pin4. By tightening the screw 14 the compression of the sealing member 2can be increased. This increases its resistance to wear and also helpsto allow for any erosion of the sealing member in operation.

In the simplified construction of Figure 3 a sealing member shown as 16performs exactly the same function as the member 12 but is not subjectedto adjustable compression. As will be seen it is located in a recessformed with a mouth of reduced area so that in effect the sealing member16 is dovetailed into the core pin 4. It may be moulded in position orsubsequently inserted.

Figure 4 shows a further modification in which a sealing member shown as17 which is cylindrical in shape is formed with a screw thread whichengages a correspond.- ing thread in a tapped bore 18 in the tip of thecore pin In each of the constructions shown the presence of therespective sealing member forms an effective seal with the rear end ofthe needle 3, thus very substantially reducmg the possibility of thecasting material entering the bore of the needle and reducing the upkeepof the mould to negligible proportions.

I claim:

1. A mold for a mount for a hypodermic needle, said mould comprising amould body having a hole at one side for the insertion of the rear endof a needle and an opening at the opposite side for the insertion of acore pin, a core pin adapted to fit within said opening, said core pinhaving a resilient sealing member at the tip there- 3. A mould for amount for a hypodermic needle ae cording to claim 1' wherein saidsealing member is fitted I within a recessin the tip of said-core pin.

References Cited in the file of this patent 4. De Reamer Oct. 21, 1931Conner Nov; 21, 1933 Dorner Dec. 28, 1943 Franz Ian. 1, 1952 Gookin May20, 1952 Hermann Feb. 23, 1954 Fineran May 4, 1954

